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Sulfur Fumarole.
Sulfur Fumarole.
In this recent photo taken at Puʻu ʻŌʻō Crater in Hawaii, we can see that elemental sulfur vapor escaping from the fumarole has cooled to form yellow-colored crystals around the margins of the crack.
Fumaroles are vents from which volcanic gas escapes into the atmosphere. Fumaroles may occur along tiny cracks or long fissures, in chaotic clusters or fields, and on the surfaces of lava flows and thick deposits of pyroclastic flows. They may persist for decades or centuries if they are above a persistent heat source or disappear within weeks to months if they occur atop a fresh volcanic deposit that quickly cools. Original public domain image from Flickr
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